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A275160 Least integer k such that A275663(k) = n. 0
1, 4, 3, 9, 27, 133, 315, 841, 747, 4485, 2799, 14175, 287061, 530079, 3061987 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Least integer k such that the number of perfect squares in {k, f(k), f(f(k)),...,1} is equal to n, where f is the Collatz function.

a(n) <= 4^(n-1). - Robert G. Wilson v, Nov 16 2016

LINKS

Table of n, a(n) for n=1..15.

Index entries for sequences related to 3x+1 (or Collatz) problem

EXAMPLE

a(5) = 27 because A275663(27) = 5. The Collatz trajectory of 27 contains the squares 484, 121, 16, 4 and 1. The other values m with the property A275663(m) = 5 are 31, 33, 36, 41, 43, 47, 54, 55, 57, 62, ...

MATHEMATICA

f[n_]:=n/2/; Mod[n, 2]==0; f[n_]:=3 n+1/; Mod[n, 2]==1; g[n_]:=Module[{i, p}, i=n; p=1; While[i>1, If[IntegerQ[Sqrt[i]], p=p+1]; i=f[i]]; p]; Do[k=1; While[g[k]!=m, k++]; Print[m, " ", k], {m, 1, 13}]

CROSSREFS

Cf. A006577, A275663.

Sequence in context: A319311 A107381 A242531 * A132192 A147756 A213768

Adjacent sequences:  A275157 A275158 A275159 * A275161 A275162 A275163

KEYWORD

nonn,more

AUTHOR

Michel Lagneau, Nov 13 2016

EXTENSIONS

a(14)-a(15) from Robert G. Wilson v, Nov 16 2016

STATUS

approved

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Last modified May 25 03:14 EDT 2019. Contains 323539 sequences. (Running on oeis4.)